1968 CA77 motor not running

Mpins921 · Post by **Mpins921** » Fri Jun 14, 2013 9:44 am

I have a 1968 Honda Dream that I'm trying to bring back to life. I'm having alot of trouble with the motor and have a few questions. First we put on different mufflers with bigger airflow, does that a effect on how well the engine runs? are these motors very particular about the mufflers they need? Also do the carborators need to be set a specific way? The problem with the bike is that it idles for a little bit then dies, while also backfiring often. One of the cylinders is not up to full compression, but is not too low. Do these motors require full compression? Any help on this would be very much appreciated.

cadman · Post by **cadman** » Fri Jun 14, 2013 8:51 pm

These are very tolerant motors. Exhaust makes little difference - just may make the mixture a bit rich or lean. The points and timing must be set properly. Valve adjustment needs to be close to correct. Carb float level needs to be correct and the carb needs to be clean. You must have a good battery (12.5VDC).

Backfiring can be a result of any mis-adjustment of these items. Check the plug color to see if both cylinders are about the same. Just what is the compression and what's the difference - "not too low" doesn't tell us much.

Mpins921 · Post by **Mpins921** » Fri Jun 14, 2013 9:03 pm

Thank you for your input, the compression is 90 and 150, what do you mean when you say to check the color of the plugs? Also am I correct in saying that the carburetor needs to be set to a specific setting. I have cleaned out them already. How would I make the mixture more lean or heavier? Once again thank you for answering my questions.

cadman · Post by **cadman** » Fri Jun 14, 2013 9:15 pm

First there is a BIG difference between 150 and 90 compression.

Plug color will tell you what is happening in each cylinder. Here is a link on reading plug color.

http://www.ngksparkplugs.com/tech_suppo ... aqread.asp

Normally we would expect each plug to about the same - I your case with 60psi difference the plugs will never be the same.

Exactly how did you clean the carbs. Taking the float bowls off and cleaning them will not do it. They need to be soaked in carb cleaner overnight the blown out with air. There are some very small orifices that need to be clean. Float levels need to be properly set. I think you are talking about external adjustments which are worthless if the internals are not absolutely clean.

Mixture can be changed by different main jets and different float levels.